IB/core: Fix deadlock on uverbs modify_qp error flow

The deadlock occurs in __uverbs_modify_qp: we take a lock (idr_read_qp)
and in case of failure in ib_resolve_eth_l2_attrs we don't release
it (put_qp_read).  Fix that.

Fixes: ed4c54e5b4ba ("IB/core: Resolve Ethernet L2 addresses when modifying QP")
Signed-off-by: Moshe Lazer <moshel@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index b7943ff16ed3f2edece8ec4cc3c7931594bd943a..6c52e72f8d2cf95f4faae1878bb8a076b73593ec 100644 (file)
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -2091,20 +2091,21 @@ ssize_t ib_uverbs_modify_qp(struct ib_uverbs_file *file,
        if (qp->real_qp == qp) {
                ret = ib_resolve_eth_l2_attrs(qp, attr, &cmd.attr_mask);
                if (ret)
-                       goto out;
+                       goto release_qp;
                ret = qp->device->modify_qp(qp, attr,
                        modify_qp_mask(qp->qp_type, cmd.attr_mask), &udata);
        } else {
                ret = ib_modify_qp(qp, attr, modify_qp_mask(qp->qp_type, cmd.attr_mask));
        }
 
-       put_qp_read(qp);
-
        if (ret)
-               goto out;
+               goto release_qp;
 
        ret = in_len;
 
+release_qp:
+       put_qp_read(qp);
+
 out:
        kfree(attr);